Flexible guard for bushing terminals



Dec. 22, 1936. H. B. KEATH FLEXIBLE GUARD FOR BUSHING TERMINALS Filed June 28, 1954 Inventdr H.B. KEATH BY I Patented Dec. 22, 1936 PATENT OFFICE FLEXIBLE GUARD FOR BUSHING TERMINALS Howard B. Keath,

St. Louis, Mo., assignor to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application June 28, 1934, Serial No. 732,769

4 Claims.

My invention relates to guards and more particularly to guards for the exterior terminal end of a stud type bushing employed in insulating a transformer conductor from the transformer housing. In bushings of this type the bare end of the conductor exterior of the transformer housing is connected directly to the bare terminal end of the bushing which is connected to V the transformer proper. It has been the practice in the past to cover and insulate this connection by wrapping insulating tape around the bare parts but this procedure is slow and expensive and, furthermore, it makes repairing difficult due to the necessity of cutting and peeling off the tape. Glass cups havealso been used as guards for the terminal end of the bushing but they have been found to be undesirable since the fragile glass will not withstand the rough handling received from construction and repair men.

One of the objects of my invention is to provide a guard or boot for the exterior terminal end of an insulating bushing which is made of flexible material and is adapted to completely cover the bare terminal and the bare end of the conductor connected thereto.

Another object of my invention is to provide a flexible boot for the terminal end of an .insulating bushing which is readily adaptable to different types of bushings and to different size conductors connected to the terminal of the bushings. I

A more specific object of my invention is to provide a tubular corrugated boot of rubber for the terminal end of a bushing, which boot is provided with openings in its wall to permit drainage of water from the interior thereof.

Still another object of my invention is to provide a guard for the terminal of an insulating bushing and the conductor connected therewith which is unbreakable, economical to manufacture, and easily attached and detached.

Other objects of my invention will become apparent from the following description taken in 45 connection with the accompanying drawing in which Figure 1 is a side view of an insulating bushing provided with my improved guard; Figure 2 is a cross-sectional view of the structure shown in Figure 1; and Figure 3 is a cross-sec- 50 tional view of a slightly modified construction.

Referring to the drawing in detail, the numeral I indicates the wall of a transformer housing which is provided with an opening 2 for receiving the corrugated porcelain member 3 of a stud type insulating bushing. The member 3 is the bare en'd provided with a shoulder 4 and with suitable fastening means broadly indicated at 5 for detachably clamping the bushing to the wall I. The conductor 6, which is attached to the transformer within the housing, extends into the bore 5 1 of the porcelain member and has its bare end secured by solder in one end of a stud 8, the other end of the stud extending to the exterior of the bore and being provided with a threaded portion 9. The stud is prevented from rotation 10 in the member 3 by means of a key In fitting in a groove H. The threaded end 9 of the stud has secured thereto a member l2 upon which lies a member I 3 adapted to be clamped thereto by means of U-bolts I4 in a well known man- 15 ner. Between these members l2 and 13 extends the bare end 15 of the insulated conductor l6 forming the outgoing lead of the transformer.

A gasket I1 is provided between the porcelain member and the member l2 to make the assemd bly oil-tight.

In accordance with my invention I provide a flexible boot I8 as an insulating means and guard for therexposed members l2 and 13 forming the terminal end of the bushing and the bare end l5 of the conductor Hi, the boot It! being preferably made of rubber. The boot is tubular in form and provided with a plurality of corrugations between its ends. One end of the boot has an inwardly extending integral o flange l9 which is adapted to be stretched and slipped over the end corrugation 20 of the porcelain member 3 to detachably secure that end to the bushing proper. The other end of the boot has a plurality of stepped integral cylindricaf'portions 2|, the smallest of which is adapted to snugly fit around the conductor I6. In order to provide for the drainage of any water that may collect in the interior of the boot, the wall thereof is formed with a plurality 40 of openings 22, as shown, the openings being so placed as to insure drainage when the bushing is either horizontally or vertically positioned.

My novel guard is very readily installed and also readily detachedto permit of repair. In installing the boot the conductor I6 is unclamped from the members l2 and I3, if not already so, and" the boot is slipped over the end of the wire to such an extent that the boot can be longitudinally compressed sufliciently that IS of the conductor can be clamped between the members I2 and I3. The boot is then permitted to become extended so that the flange l9 may be stretched and slipped over the corrugations 20 on the porcelain member 3.

The stepped cylindrical portions are provided on the conductor end of the boot in order to adapt the boot to different size conductors. All that is necessary to secure a larger opening is to sever the desired number of cylindrical portions from the boot. In Figure 3, I have shown the boot fltted to a larger size conductor 16', the inner cylindrical portion 2| being clipped off. In Figure 3, I have also shown the boot applied to a bushing wherein the porcelain member 3 is of smaller diameter. In order to provide a proper attaching rib, a washer 23 is placed between the member l2 and the porcelain member 3, which washer has slipped over it the flanged portion l9 of the boot.

From the foregoing description of my invention it is readily seen that I have constructed a very efllcient boot for the terminal end of a standard type bushing which both insulates and guards the bare parts thereof. The boot is unbreakable and is readily attached and detached. The boot is also adaptable for use with different size bushings and conductors, thus making it possible to reduce the number of different size boots necessary to carry in stock to flt the varying sizes of bushings and conductors. The boot, because of its flexibility and corrugated form, also readily adapts itself to conditions where the conductor I6 is bent at an angle to the axis of the bushing adjacent the terminal thereof. My novel boot also permits the drainage of water from the interior of the boot in all of its positions.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. A flexible tubular insulating boot for totally enclosing and protecting the connection between an electrical conductor and the exterior terminal end of a transformer bushing on a transformer housing, said boot having a cylindrical intermediate portion, one end of the boot having an inwardly extending annular attaching flange and the other end which is adapted to surround and grip a conductor being formed with a plurality of stepped integral cylindrical portions the largest of which is adjacent the main body of the boot whereby the internal diameter of the opening in said last named end may be increased by severing one or more of said cylindrical portions from the boot, the largest of said stepped cylindrical portions being substantially of less diameter than the diameter of the boot and the over-all length of said stepped portions being a fraction of the length of the remainder of the boot.

2. A flexible tubular insulating boot for totally enclosing and protecting the connection between an electrical conductor and the exte- 'rior terminal end on a transformer bushing on a transformer housing, said boot having a cylindrical intermediate portion, one end of the boot having an inwardly extending annular attaching flange and the other end which is adapted to surround and grip a conductor being formed with a plurality of stepped integral cylindrical portions the largest of which is adjacent the main body of the boot whereby the internal diameter of the opening in said last named end may be increased by severing one or more of said cylindrical portions from the boot, the largest of said stepped cylindrical portions being substantially of less diameter than the diameter of the boot and the over-all length of said stepped portions being a fraction of the length of the remainder of the boot, said boot also being provided with an opening in its wall for permitting water to drain from the interior thereof.

3. A flexible tubular insulating boot for totally enclosing and protecting the connection between an electrical conductor and the exterior terminal end of a transformer bushing on a transformer housing, said boot being corrugated over an intermediate portion to permit the boot to be longitudinally collapsed, one end of said boot having an inwardly extending annular attaching flange and the other end which is adapted to surround and grip a conductor being formed with a plurality of stepped integral cylindrical portions the largest of which is adjacent the body of the boot whereby the internal diameter of the opening in said last named end may be increased by severing one or more of said cylindrical portions from the boot, said stepped cylindrical portions having an over-all length substantially less than the length of the remainder of the boot.

4. A flexible tubular insulating boot for totally enclosing and protecting the connection between an electrical conductor and the exterior terminal end of a transformer bushing on a transformer housing, said boot being of cylin-.

drlcal formation over a portion of its length and corrugated over the remainder, the end adjacent the corrugated portion having an inwardly extending annular attaching flange and the other end adjacent the cylindrical portion which is adapted to surround and grip a conductor being formed with a plurality of stepped integral cylindrical portions the largest of which is adjacent the cylindrical portion whereby the internal diameter of the opening in said last named end may be increased by severing one or more of said cylindrical portions from the boot, said stepped cylindrical portions having an over-all length substantially less than the length of the remainder of the boot.

HOWARD B. KEATH. 

